Semiconductor Isolation Circuit Layout for High-Voltage Breakdown

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Solution Overview

Problem

Conventional semiconductor integrated circuits with insulation circuits, such as photocouplers or digital isolators, face issues with insulation reliability between high-voltage and low-voltage circuits due to electrical breakdown in the insulating portion, leading to a loss of insulation between the CPU and high-voltage systems.

Innovation Solution

A semiconductor integrated circuit design that includes a first circuit driven by a high voltage, a second circuit that outputs a low-voltage control signal, and a series connection of insulation circuits with insulating elements that magnetically or capacitively couple the control signal to ensure reliable insulation and prevent voltage leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single insulation circuit with an insulating portion composed of an organic compound is used to isolate high-voltage and low-voltage circuits, then signal transmission is achieved, but insulation reliability deteriorates due to electrical breakdown under high voltage stress

Engineering Contradiction:

Improveinsulation reliabilityVSAvoidelectrical breakdown

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides a single insulation circuit into multiple insulation circuits connected in series between the high-voltage first circuit and the low-voltage second circuit. Each insulation circuit contains an insulating portion with an organic compound. This segmentation ensures that if one insulating portion breaks down due to electrical stress, the other insulating portions maintain the insulation barrier, preventing complete loss of isolation between high-voltage and low-voltage circuits.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the insulating portion is exposed to high voltage equal to or greater than its dielectric strength, then signal transmission may occur, but the insulating property is lost and short-circuit current flows

Engineering Contradiction:

Improveinsulation reliabilityVSAvoiddielectric strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent prepares compensatory measures in advance by configuring multiple insulation circuits in series. This redundancy acts as a cushion against the harmful effect of electrical breakdown. When one insulating portion experiences voltage stress exceeding its dielectric strength and breaks down, the remaining intact insulating portions continue to provide insulation, cushioning the system against complete insulation failure and preventing short-circuit current flow.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed design enhances insulation reliability between high-voltage and low-voltage circuits by ensuring secure insulation even if an electrical breakdown occurs in one insulation circuit, thereby maintaining system insulation and preventing voltage leakage.

Implementation Method 1

Each insulation circuit is configured to magnetically couple or capacitively couple the control signal in the insulating element to transmit the control signal from the second circuit to the first circuit

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 3

Applying a voltage equal to or greater than a dielectric strength across the insulating portion within the isolator produces an electrical breakdown to pass a short-circuit current through the insulating portion

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS12243857B2Semiconductor integrated circuit

Publication Date: 2025.03.04 MITSUBISHI ELECTRIC CORP

AI summary

Provided is a semiconductor integrated circuit that improves insulation reliability between a high-voltage circuit and a low-voltage circuit. The semiconductor integrated circuit includes the following: a first circuit controlled by a control signal of low voltage and driven at a higher voltage; a second circuit configured to output the control signal to the first circuit to control the driving of the first circuit; and a plurality of insulation circuits each including an insulating element, the plurality of insulation circuits connecting between the first and the second circuits in series. Each insulation circuit is configured to magnetically or capacitively couple the control signal in the insulating element to transmit it from the second circuit to the first circuit, and is configured to insulate the first circuit from the second circuit in the insulating element to prevent the higher voltage from being applied from the first circuit to the second circuit.